Evaluation of traits related to the biological nitrogen fixation in Melilotus albus half-sib families

In this study, half-sib families of Melilotus albus populations were established in two different locations (Yuzhong and Linze) and their phenotypic variations in relation to biological nitrogen fixation (BNF) were evaluated. Root dry weight (RW), number of nodules per plant (NN), nodule weight (NW), leaf total nitrogen (LTN), leaf total phosphorus (LTP) and the percentage of nitrogen derived from the atmosphere (%Ndfa) in plant leaves were measured. The results showed that the coefficients of variation for these indices were greater than 15%, and principal component analysis identified four groups of half-sib families. The RW, NN, NW, LTN, LTP, and %Ndfa values of group 1 were 4%, 26%, 10%, 17%, 21%, and 11% higher, respectively, than in the control (RX-02). The maximum and minimum values of %Ndfa for half-sib families were 58% and 43%, respectively.The progeny families with good biological nitrogen fixation traits selected in this study can lay a foundation for further breeding of new varieties with strong biological nitrogen fixation ability.